A general theory for the dynamics of aspherical droplets useful to interpret frequency spectra more accurately for thermophysical property measurements was developed. The oscillations of a non-spherical droplet oscillating about an oblate spheroid subjected to external forces are considered. The effect of the static deformation and the interaction between the drop oscillation and the external field on the resonance are investigated. The analysis developed can be extended to consider different static shape deformation shapes. In order to validate the analytical predictions and to conduct further investigations, an experimental apparatus and a novel experimental procedure were developed. Experimental data and observations on the frequency splitting and surface tension, and the dynamics of the droplet in the experimental apparatus are presented. Finally, the effect of fullerenes on some dynamic features of levitated droplets is investigated.

In linguistic research, current practices of recording audio data involves a mixture of analogue and digital technologies giving little forethought to methodological issues and insight into the consequences of using one technology over the other. Analogue recorders are inherently flawed and are not ideal for acoustic analysis. With the introduction of digital recorders into the consumer market, it is difficult to decide which recorder is best suited for linguistic and acoustic analysis. The MiniDisc, introduced by Sony in 1992, is a magneto-optical recorder that offers 'CD-like' quality, in a compact and shock-resistant system, thus making it a potential tool for linguistic field research. However it is not known how the psycho-acoustically based compression system, ATRAC, affects the spectrum of speech sounds. This thesis compares the MiniDisc with a DAT recorder and analyses the differences using spectral and spectrographic analyses. In addition, this thesis tries to establish sound practices for using the MiniDisc in linguistic research.

No description available.

One of the most important problems to be faced when building a speech recognizer is the lack of sufficient training data to estimate all of the parameters of the system. One of the most successful techniques addressing this problem is to decrease the number of parameters in the system by the use of classification-tree based acoustic models. In this thesis, several variations on this theme will be presented, the first few ones dealing with trees classifying whole HMMs (tree units), the others with trees classifying states of HMMs (tree states). Results obtained on the Air Travel Information System (ATIS) task show that using classification trees produces systems with up to 90% less models (and proportionally less parameters to estimate) with no loss of performance.

In-line monitoring of die-casting of aluminum (A356, A357, 86S), magnesium (AZ91) and a metal matrix composite (Gra-NiRTM 6S:3G) will be monitored using the reflection coefficient obtained by using an ultrasonic technique, the pulse/echo. For each of the materials enumerated above, the average temperature of the mold through its thickness, the end of filling of the part, the solidification of the part in the cavity of the mold, the gap and/or the detachment of the part, the sound velocity and the attenuation of the material will be measured by this ultrasonic technique during the process. / For the materials the melt temperature will not exceed 600°C because the casting is made at the semi-solid state, between the solidus and liquidus, of the materials. A novel high performance buffer rod with a cooling system is integrated into the die. Therefore, ultrasonic measurements can be carried out with high signal-to-noise ratio at elevated temperatures.

<p> The field of shock physics as a whole has only recently begun to pay particular attention to modeling heterogeneous materials under shock loading. These materials are important because of their practicality in terms of creating stronger, more shock resistant materials. To understand why they absorb shock impact energy better than homogeneous materials means that the small-scale processes that occur during the shock loading of these heterogeneous materials needs to be understood. Recent computational experiments, called mesoscale simulations, have shown that explicitly incorporating small-scale heterogeneous features into hydrocode simulations allows the bulk shock response of the heterogeneous material to be observed while not requiring the use of empirically determined constitutive equations. Including these features in simulations can offer insights into the irreversible mechanisms that dominate the propagation of shock waves in heterogeneous materials. </p><p> Three cases where the mesoscale approach for modeling the dynamic shock loading of heterogeneous materials are presented. These materials fall into three categories: granular - dry sand, granular with binder - concrete, and granular contained in a metal foam with a binder - granular explosive contained in an aluminum foam. The processes in which shock waves propagate through each material are addressed and relationships between the three materials are discussed. Particle velocity profiles for dry sand and concrete was obtained from Harvard University and Eglin Air Force Base, respectively. Mesoscale simulations using CTH are conducted for each type of heterogeneous material and the results are compared to the experimental data.</p>

Thesis (Ph.D.)--The Pennsylvania State University, 2006. / (UMI)AAI3229387. Adviser: Sridhar Anandakrishnan. Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4471.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7382. Adviser: Henrique Reis. Includes bibliographical references (leaves 314-326) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6819. Adviser: Kenneth S. Suslick. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Sound propagation is a complex subject, especially in an enclosure. The study of room acoustics involves not only a research into how sound is propagated in a room, but also a search into how to measure sound under different condition and how to control sound in the case of various wall materials. For an acoustical environment, there are three separated parts: sound sources, room acoustics, and the listens. These three items form a source-medium-receiver chain, which is typical for most of communication models. In this thesis, the image method is applied to predict the acoustical quality of a real room, and the experiment for room acoustic measurement is set up. The simulation model using image method proved the design of the measurement system is efficient for room acoustics.